In this night (27th of Ramadan), the Holy Quran was sent down from LOH-E-MEHFOOZ (the Preserved Tablet) to the earth. Messenger of ALLAH (Blessings of Allah and peace be on him) told us to search for Shab-e-Qadr in the odd numbered nights, in the last ten days of Ramzan. So, the 21st, 23rd, 25th, 27th or 29th night of Ramadan could be Shab-e-Qadr.